1. Field of the Invention
The present invention relates to a method for fluorometric analysis for catecholamine using 1,2-diphenylethylenediamine.
2. Discussion of the Background
Catecholamine is a general term of biogenic amines having a 3,4-dihydroxyphenyl group. In particular, catecholamines such as norepinephrine, epinephrine, dopamine and the like which are metabolites of tyrosine are performing an important function as the adrenal medulla hormones or as the neurotransmittors at the end of the sympathetic nerves. Therefore, the analysis of catecholamine is indispensable for the studies of the endocrinium and the nervous system. However, the content of catecholamine is extremely low in the tissue; it is no more than 1/10.sup.4 of amino acid, so the analytical method with high sensitivity is required. Recently, high sensitivity fluorometric analysis of catecholamine attracted attention as a clinical application.
Although there is a method for measuring the native fluorescence of catecholamine at pH 1, it is not specific for catecholamine and the sensitivity is not so high. One method which is adopted most popularly is to determine the fluorescence of trihydroxyindole (THI) formed by treating catecholamine with the oxidizing agent. This method has high sensitivity particularly to norepinephrine and epinephrine. But, dopamine, is resistant to the oxidation and its detection cannot be achieved with sufficient sensitivity even by the THI method. Another method is also known which determines catecholamine through the condensation reaction with ethylenediamine, but it has shortcomings in that the procedure is complicated and the sensitivity is low.